No transparency on a data package sold to me.

So I had a representative call em from Rewards co call me, on behalf of MTN, to sell me a data sim. The lady I spoke to assured me that I would receive 20GB day + 20GB night data, at only R199pm .Sounded like a pretty okay deal to me , since I always spend a lot of money on data. So I agreed. Then the simcard was delivered, then I only got 5GB day + 5GB night, plus some other 5GB which made it 15GB for R265 pm. Was pretty ridiculous to me and wasn’t what I signed up for. So I called into Mtn multiple times to get understanding and assistance, I was kept on hold for +\- 3hrs, just to speak to someone. & eventually, I got a Lady to help me , a month after all this trouble! She then advised me to call Rewards co. So I can get a contract, then we can sort it out. She gave me a number, I then called Rewards co. Spoke to a guy, seemed willing to help, asked for my ID number to check on their system, as I was giving it to him, he dropped the call on me, I am furious! And very upset at the level of service I’ve been getting, & the treatment, All I wanna do is cancel this contract. & I’m not willing to pay anything until it’s sorted out. No transparency what so ever!